Photographic products and processes using alkali permeable co-polyeric layers



Dec. 18, 1962 H. c. HAA PHOTOGRAFI-IIC PRODUCTS ANDSPROCESSES USING 3069264 ALKALI PERMEABLE (JO-POLYMERIC LAYERS Filed Dec. 17, 1958 N N-DIETHYLACRYLAMIDE-ACRYLIC ACID COPOLYMER LAYER CONTAINING A COLOR-PROVIDING SUBSTANCE \PHOTOSENSITIVE LAYER SUPPORT OF N,N-DIETHYLACRYLAMIDE 2o ACRYLAMIDE COPOLYMER CONTAINING 22 CYAN DYE DEVELOPER RED-SENSITIVE EMULSION NTERLAYER lllll LAYER OF N,N-DIETHYLACRYLAMIDE 3O ACRYLAMIDE COPOLYMER CONTAINING 32 MAGENTA DYE DEVELOPER EN* SENSITIVE EMULSION 36 NTERLAYER YER OF N,N-D|ETHYLACRYLAMIDE- ACRYLAMIDE COPOLYMER ,CONTAINING YELLOW DYE DEVELOPER UE-SENSITIVE EMULSION FIG.2

IN VENT 0R.

: ATTO NEYS United States Patent Gfitice ware Filed Dec. 17, 1958, Ser. No. 781,068 17 Claims. (Cl. 96-29) The present invention is concerned with photography and more particularly with novel photographic products and novel photographic processes utilizing said products.

One object of the present invention is to provide mechanically stable novel photosensitive elements for color diffusion transfer processes.

Another object of the present invention is to provide improved color diffusion transfer processes utilizing said photosensitive element.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation and order of one or more of such steps with respect to each of the others, and the product possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanyin g drawing wherein:

FIGURE 1 is a digrammatic cross-sectional view of one embodiment of a photosensitive element of this invention; and

FIG. 2 is a diagrammatic cross-sectional view of one embodiment of a multilayer photosensitive element Within the scope of this invention.

The present invention is diffusion transfer processes. sensitive element including a silver halide emulsion layer is exposed to create therein a latent image. The latent image is developed and, concurrent with and under the control of this development, an irnagewise distribution of mobile color-providing substances is formed. At least a portion of these color-providing substances is transferred by means of an alkaline aqueous processing liquid to a superposed image-receiving layer to form a colored image thereon. As examples of such processes, mention may be made of the processes disclosedand claimed in the copending U.S. application of Howard G. Rogers, Serial No. 748,421, filed July 14, 1958 (now U.S. Patent No. 2,983,- 606 issued May 9, 1961), as a continuation-in-part of U.S. application, Serial No. 415,073, filed March 9, 1954 (now abandoned), wherein dye developers (i.e., compounds which contain in the same molecule both the chromophoric system of a dye and also a silver halide developing function) are the color-providing substances, the processes disclosed and claimed in U.S. Patent No. 2,647,049, issued July 28, 1953, to Edwin H. Land, wherein color developers are employed to develop the latent image and color couplers are the color-providing substances, and the processes disclosed in U.S. Patent No. 2,774,668, issued December 18, 1956, to Howard G. Rogers, wherein complete, preformed dyes are used as the color-providing substances. The termv color-providing substances, as used herein, refers to organic materials such as dyes, including dye developers and dye intermediates.

In an especially useful mode of carrying out color diffusion transfer processes such as described above, the

particularly related to color In such processes a photo- 3,069,264 Patented Dec. 18, 1962 color-providing substances are disposed in a separate alkali-permeable layer in the photosensitive element. The

separate alkali-permeable layer may be placed either in.

front of or behind the photosensitive emulsion with which it is associated; however, in a preferred embodiment it is placed behind, i.e., on the side of the emulsion which is most distant from the photographed subject when the emulsion is exposed, and preferably also adapted to be most distant from the image-receiving element when in superposed relationship therewith. In carrying out the processes, the photosensitive element is exposed and wetted with an aqueous alkaline processing solution, for example, by immersing, coating, spraying, flowing, etc., in the dark, and the photosensitive element is superposed prior to, during or after wetting on an image-receiving element. In a preferred embodiment the aqueous alkaline processing solution contains a viscosity-increasing compound and is applied to the photosensitive element in a substantially uniform layer as the photosensitive element is brought into superposed position with the image-receiving element. The alkaline aqueous processing solution permeates the photosensitive emulsion and alkali-permeable layers and solubilizes the color-providing substances to provide a substantially uniform distribution of the color-providing substances therein. As the processes proceed, the'exposed silver halide image is developed and an imagewise distribution of mobile color-providing substances is formed. At least a portion of the mobile color-providing substances is transferred to and imbibed on the image-receiving element to form the image thereon. The image is viewed by stripping the image-receiving element from the photo:

sensitive element.

When the color-providing substances are incorporated into a separate alkali-permeable layer, it is desirable that said alkali-permeable layer have good dry adhesion to the other layers present in order to withstand the stresses and strains such a layer would be normally subjected to during,

. for example, coating operations, and especially to withstand the stresses and strains which are encountered if the photosensitive element is a part of a roll film unit. Such adhesion must be achieved in the presence of relatively high amounts of the color-providing substances which generally have little or no adhesiveness in themselves and which often have an adverse effect on the bonding. It is further desirable, and no less important, that said alkalipermeable layer have good wet adhesion to the other layers present; otherwise, during processing, the image-receiving element from the photosensitive element, delamination may take place and portions of the photosensitive element would adhere to the surface of the image-receiving element and mar the quality of the transfer image. It is still further desirable that the alkalipermeable layer readily release the color-providing substances in order to make the maximum amount of said substances available for forming the image. In the past, film-forming polymers such, for example, as cellulose acetate hydrogen phthalate have been proposed as materials for the alkali-permeable layers. a

It has been discovered that when the color-providing substances are disposed in a layer comprising:

(A) Copolymers of N,N-dia1kyl-a,;3-unsaturated carboxamides with monomers selected from the group consisting of cap-unsaturated carboxylic acids and unsubstituted amides of such acids,

' superior to that obtained with cellulose acetate hydrogen upon stripping Q3 phthalate and, further, said copolymers readily release the color-providing substances.

The usefulness of the copolymers of this invention is especially demonstable when dye developers are the colorproviding substances. Dye developers, as noted above, are compounds which contain in the same molecule both the chromophoric system of a dye and also a silver halide developing function. By a. silver halide developing function is meant a radical which is capable of developing an exposed silver halide image. Particularly useful dye developers are those in which the silver halide developing function is provided by the presence of a benzenoid developing radical. A preferred benzenoid developing radical in such compounds is a hydroquinonyl radical. Examples of representative dye developers are given in the previously mentioned U.S. application of Howard G. Rogers, Serial No. 748,421. Additional useful dye developers are described in the following copending U.S. applications:

Application Serial No. 449,514, filed August 12, 1954, in the names of Elkan R. Blout and Myron S. Simon, now abandoned and replaced by continuation-in-part application Serial No. 849,727, filed October 30, 1959.

Application Serial No. 471,542, filed November 26, 1954, in the names of Elkan R. Blout, Saul G. Cohen, Milton reen, Howard G. Rogers, Myron S. Simon and Robert B. Woodward, now abandoned and replaced by continuation-in-part application Serial No. 1,442, filed January 11, 1960.

Application Serial No. 478,922, filed December 30, 1954, in the names of Elkan R. Blout, Marilyn R. Cohler, Milton Green, Myron S. Simon and Robert B. Woodward, now abandoned and replaced by continuation-inpart application Serial No. 824,785, filed July 3, 1959.

Application Serial No. 612,045, filed September 25, 1956, in the names of Elkan R. Blout, Milton Green and Howard G. Rogers, now abandoned and replaced by continuation-impart application Serial No. 144,816, filed October 18, 1961.

Application Serial No. 612,052, filed September 25, 1956, in the names of Milton Green and Howard G. Rogers, now abandoned and replaced by continuation-in-part application Serial No. 165,930, filed January 12, 1962.

Application Serial No. 612,053, filed September 25, 1956,

in the name of Myron S. Simon.

Application Serial No. 612,054, filed September 25, 1956, in the names of Helen P. Husek and Myron S. Simon. Application Serial No. 612,055, filed September 25, 1956,

in the name of Helen P. Husek.

Application Serial No. 755,804, filed August 18, 1958, in the names of Elkan R. Blout, Saul G. Cohen, Milton Green and Myron S. Simon.

In color diffusion transfer processes employing dye developers, the dye developer, as mentioned previously for color-providing substances in general, is preferably placed in a separate alkali-permeable layer behind the photosensitive layer. Upon processing, the alkaline aqueous processing solution permeates to the separate alkalipermeable layer and solubilizes the dye developer therefrom. As the process proceeds, the latent silver halide image in the photosensitive element is developed and, as a result, of this development, the dye developer in the exposed areas is oxidized and substantially immobilized. At least a portion of the unreacted dye developer is imbibed on a superposed image-receiving element to create thereon the positive dye image. In such processes the immobilization of the dye developers in the exposed areas is apparently due, at least in part, to a change in the solubility characteristics of the dye developer upon oxidation. It may also be due in part to a tanning effect on the emulsion by the oxidized developer and to localized exhaustion of alkali due to development.

FIG. 1 of the accompanying drawing illustrates one embodiment of a photosensitive element for use in color diffusion transfer processes wherein a N,N-diethylacrylamide-acrylic acid copolymer is used as the material for a separate alkali-permeable layer. The photosensitive element shown therein comprises a support 10, a layer 12 of N,N-diethylacrylamide-acrylic acid copolymer containing a color-providing substance and a photosensitive layer '14.

In preparing photosensitive elements of the type mentioned above and in preparing other photosensitive elements within the scope of this invention, the copolymer layers may be conveniently applied from coating solutions containing the desired copolymer. The preferred coating solutions comprise 2 to 10% of copolymer; however, this amount may be varied to suit particular needs. The coating and drying operations may be carried out according to procedures well known to the art. The color-providing substances which are to be disposed in the separate alkalipermeable layer may be incorporated into the coating solution and applied therewith, or they may be imbibed onto the layer after its application. When the colorproviding substances are incorporated into the coating solutions, they may be dispersed or solubilized therein, depending upon the color-providing substance itself, the solvent used and the state desired for the diffusion transfer processes. As examples of suitable solvents which can be used in preparing the coating solutions, mention may be made of methanol, ethanol, and methanol-tetrahydrofuran mixtures. When the coating solution is applied directly to a support such, for example, as baryta, cellulose acetate, etc., said support may be first subcoated with suitable subbing materials to further enhance the adhesion.

The copolymers of this invention are also suitable as materials for alkali-permeable layers in integral multilayer photosensitive elements for use in multicolor diffusion transfer processes. As an example of such photosensitive elements, mention may be made of the photosensitive elements disclosed and claimed in the copending U.S. application of Edwin H. Land and Howard G. Rogers, Serial No. 565,135, filed February 13, 1956, wherein at least two selectively sensitized photosensitive strata are superposed on a single support and are processed, simultaneously and without separation, with a single common image-receiving element. A suitable arrangement of this type comprises a support carrying a redsensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum and a blue-sensitive silver halide emulsion stratum, said emulsions having associated therewith, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer. In one of the preferred embodiments of photosensitive elements of this type, the dye developers are disposed in separate alkalipermeable layers behind the photosensitive silver halide emulsion stratum with which they are associated. As in monochromatic photosensitive elements, the copolymers of this invention, when used as materials for the alkali-permeable layers, provide superior wet and dry adhesion, as compared with cellulose acetate hydrogen phthalate, and also readily release the color-providing substances. When the polymers of this invention are used in such multicolor film units, at least one and usually all the color-providing substances are disposed in layers comprising the polymers of this invention. However, it should be understood that in certain instances it may be desirable, for reasons such, for example, as permeation rates, transfer rates, etc., to dispose some of the colorproviding substances in the silver halide emulsions or in alkali-permeable layers of materials other than those disclosed herein.

A multilayer photosensitive element of the type mentioned above is illustrated in FIG. 2 of the accompanying drawing. A support 20 carries a layer 22 of a N,N- diethylacrylarnide-acrylamide copolymer containing a cyan dye developer; a layer 24 of a red-sensitive silver halide emulsion; an interlayer 26, e.g., polyvinyl alcohol, gelatin, etc. a layer 28 of a N,N-diethylacrylamide-acrylamide copolymer containing a magenta dye developer; a layer 30 of a green-sensitive silver halide emulsion; an interlayer 32; a layer 34 of N,N-diethylacrylamideacrylamide copolymer containing a yellow dye developer; and an outermost layer 36 of a blue-sensitive silver halide emulsion. In certain instances, for example, when the yellow dye developer is not present in a state capable of functioning as a filter, a yellow filter is placed in interlayer 32.

Although the N,N-diethylacrylamide-acrylamide copolymer layers in the photosensitive element of FIG. 2 are shown principally adhered to gelatin or polyvinyl alcohol layers, it should be noted that the copolymers of this invention show good adhesion to hydrophilic, alkali permeable film-forming materials in general. As a result of this, wide discretion may be exercised in selecting film-forming materials as carriers for the silver halide emulsion, interlayers, and. other layers which may be adjacent to the copolymer layers. For example, one may replace gelatin, which is the carrier usually used in the silver halide emulsion layers, in whole or in part, with gelatin substitutes such, for example, as cellulose ethers, polyvinyl alcohols, partially hydrolyzed organic esters of polyvinyl alcohols, acetals of polyvinyl alcohols, etc. Similar discretion may be exercised in selecting the filmforming materials for the interlayers and other layers. In certain instances, if desired, the copolymers of this invention may be used as the carrier in interlayers and other layers.

Although the copolymers of this invention provide good adhesion in and by themselves, in certain instances their adhesion to adjacent layers may be enhanced by incorporating a small amount of said copolymers into the layers to which they are to be adhered. The amount of copolymer, so incorporated, may be varied to suit particular needs; generally, however, an amount comprising about by weight, of the adjacent carrier material will provide the increased adhesion.

Both the monochromatic and multicolor photosensitive elements within the scope of this invention may be used in roll film units which contain a plurality of photosensitive frames. The photosensitive elements of this invenvention are especially useful in composite roll film intended for use in a Polaroid Land Camera, sold by Polaroid Corporation, Cambridge 39, Massachusetts, or a similar camera structure such, for example, as the camera forming the subject matter of U.S. Patent No. 2,435,717, issued to Edwin H. Land on February 10, 1948. In general, such composite roll films comprise a photosensitive roll, a roll of image-receiving material and a plurality of pods containing an aqueous alkaline processing solution. The rolls and pods are so associated with each other that, upon processing, the photosensitive element may be superposed on the image-receiving element and the pods may be ruptured to spread the aqueous alkaline processing solution between the. superposed elements. The nature and construction of the pods used in such units are well known to the art. See, for example, U.S. Patents Nos. 2,543,181 and 2,634,886, issued to Edwin H. Land.

The copolymer within Formula A may be prepared by copolymerizing a N,N-dia1kyl-substituted-a, 8-unsaturated carboxamide monomer with an 0a,,B-UI1SEllllIfllI6d carboxylic acid or an unsubstituted amide of such acid. The polymerization may be catalyzed and carried out under conditions well known to the art. The preferred monomers for use in preparing the copolymers within Formula A are those which contain less than six carbon atoms, exclusive of the N,N-dialkyl substituents which may be present. The preferred N,N-dialkyl-a,,8-unsaurated carboxamide monomers are those in which each N-alkyl substituent comprises less than five carbon atoms. As

6 examples of c p-unsaturated carboxylic acids, amides and N,N-dialkyl-substituted amide monomers which are suitable for use in preparingcopolymers within Formula A, mention may be made of acrylic acid, methacrylic acid, crotonic acid, acrylamide, meLhacrylamide, N,N-dibutylacrylamide, N N,dibutylmethacrylamide, N,N diethyl acrylamide, N,N-diethylmethacrylamide, N,N-dimethylacrylamide and N,N-dimethylmethacrylamide. In preparing the copolymers within Formula A, the molar ratio of the N,N-dialkyl-substituted monomer to the comonomer reactant can usually be varied to suit particular needs. It has been found, however, that especially useful polymers are produced by using a ratio of at least 1 to 1 when each N-alkyl substituent comprises less than three carbon atoms and by using a ratio of less than 1 to 1 when each N-alkyl substituent comprises more than three carbon atoms.

The copolymers within Formula B may be prepared by copolymerizing a N-cycloalkyl-substjtuted or a N-aralkyl-substituted-a,/3-unsaturated carboxamide mon:mer with an c p-unsaturated carboxylic acid monomer under conditions Well known to the art. The preferred monomers for use in the preparation are The are As preparing the copolymay be made of acrylic acid, methacrylic acid, crotonic acid, N-cyclohexylacryh amide, N cyclohexylmethacrylamide, N ben zylacrylamide and N benzylmethacrylamide. In preparing the copolymers within Formula B, the ratio of the N-cycloalkylor Narakyl-substituted u,;8-unsaturated carboxamide monomer to the a,fi-unsaturated carboxylic acid monomer, as in preparing the copolymers Within Formula A, can usually be varied to suit particular needs. The copolymers within Formula B which have been found to be especially useful are those in which said ratio of reac ants is at least 1 to 1.

It will be understood that unless the reaction rates of the monomers are about equal, the composition of the copolymers produced at different stages of the polymerization will vary. The preferred polymers for, use in this invention are the initial polymers produced.

The following nonlimiting examples illustrate the preparation of copolymers suitable for use in preparing the photosensitive elements of this invention.

Example 1 4.4 gms. of N,N-diethylacrylamide and 1.07 gms. of.

recrystallized acrylamide (7 to 3 molar ratio) were dissolved in 11 gms. of carbon tetrachloride containing 0.0109 gm. of azobisisobutyronitrile, and polymerized, under vacuum, at 60 C. for one hour. The resulting polymer was precipitated into hexane and purified by reprecipitation from methanol into ether. Upon drying, under vacuum, 2.4 gms. of initial polymer were obtained which was soluble cohol.

Example 3 8.45 gms. of N-benzylacrylamide and 1.62 gms. of acrylic acid (7 to 3 molar ratio) were placed in 10 ml.

those which compriseless than six carbon atoms, exclusive of the'N-cycloalkyl.

in acetone, dioxane, benzene and a1-- of carbon tetrachloride containing 0.02 gm. of azobisisobutyronitrile and heated for 3 /2 hours. The resulting initial polymer was precipitated into ether and purified by dissolving it in an ethanol-dioxane mixture and reprec1pitating it into ether. When dried, the polymer was found to be soluble in water, 2% alkali, and dioxane.

Example 4 10.65 gms. of N-cyclohexylacrylamide and 2.16 gms. of acrylic acid (7 to 3 molar ratio) were placed in 12 ml. of benzene containing 0.064 gm. of benzoyl peroxide and heated, under nitrogen, for three hours. An additional 0.064 gm. of benzoyl peroxide was added and the polymerization was continued at 65 C., under vacuum, for one hour. The resulting initial polymer was dissolved in methanol and precipitated into ether. It was insoluble in water, almost soluble in 2% alkali, and soluble in methanol and ethanol.

Example 5 14.04 gms. of .dibutylacrylamide and 12.61 gms. of acrylic acid (3 to 7 molar ratio) were distolved in 29 ml. of methanol, containing 0.0286 gm. of azobisisobutyronitrile, and polymerized at 65 C. under nitrogen. The initial polymer, which was produced, was precipitated into hexane and purified by precipitation from methanol into ether.

The following nonlimiting examples illustrate the preparation of photosensitive elements within the scope of this invention and their use in color diffusion transfer processes.

Example 6 A methanol-tetrahydroturan coating solution (1 to 1, by.- volume) comprising 2% of a copolymer of N,N-diethylacrylamide and acrylic acid (prepared as in Example 1), and 3% of 1-phenyl3-N-n-hexylcarboxam'do-4-[p- (2,5 dihydroxyphenethyl) phenylazo] 5 pyrazolone (prepared by the processes disclosed in the copending application of Elkan R. Blout, Milton Green and Howard G. Rogers, Serial No. 612,045, filed September 25, 1956) was coated on a gelatin-subcoated cellulose acetate support. When the coating solution had dried, a coating of silver iodobromide emulsion was applied.

The above photosensitive element was exposed and then processed by spreading an aqueous processing solution comprising:

Percent Sodium carboxymethyl cellulose 5.0 Sodium hydroxide 2.0 1-phenyl-3-pyrazolid0ne 0.6 2 5-bis-ethyleneiminohydroquinone 0.4 6-nitrobenzimidazole 0.12

between said photosensitive element and an image-receiving element as said elements were brought into superposed relationship. The image-receiving element ccmprised a cellulose acetate coated baryta paper which had been coated with an ethanol solution containing 4% of Nylon Type F8 (trade name of E. I. du Pont de Nemours & Co., Wilmington, Delaware, for N-methoxymethyl polyhexamethylene adipamide). After an imbibition period of approximately one minute, the image-receiving element was separated and contained a dense yellow positive dye image of the photographed subject. No signs of delamination in. the, photosensitive element were observed.

Example 7 A photosensitive element, similar to that of Example 6, was prepared using the N,N-diethylacrylamide-acrylamide copolymer prepared in Example 2. Upon processing, in a manner similar to that employed in Example 6, a dense yellow positive image of the photographed subiectwas obtained. No signs of delamination in the photosensitive element were observed.

Example 8 A photosensitive element, similar to that of Example 6, was prepared using the N-benzylacrylamide-acrylic acid copolymer as prepared in Example 3. Upon processing, in a manner similar to that employed in Example 6, a dense yellow positive image of the photographed subject was obtained. No signs of delamination in the photosensitive element were observed.

Example 9 A photosensitive element, similar to that of Example 6, was prepared using the N-cyclohexylacrylamide-acrylic acid copolymer as prepared in Example 4. Upon processing, in a manner similar to that employed in Example 6, a dense yellow positive image was obtained. No signs of wet delamination in the photosensitive element were observed.

Example 10 A photosensitive element, similar to that of Example 6, was prepared using the dibutylacrylamide-acrylic acid copolymer as prepared in Example 5. Upon processing, in a manner similar to that employed in Example 6, a dense yellow positive image was obtained. No signs of wet delamination were observed.

In the above examples, the dry adhesion of the copolymer layers was tested by adhering a strip of an adhesive film to the photosensitive element, stripping it from the element and observing for delamination. Each of the photosensitive elements, prepared in the above examples, was superior to similar photosensitive elements prepared with cellulose acetate hydrogen phthalate as the dye carrier. The dry adhesion was further tested by bending the photosensitive elements over rods of various diameters and examining for delamination. In each instance the photosensitive elements of this invention could be bent to a sharper angle than similar elements using cellulose ing signs of delamination.

As mentioned previously, the polymers of this invention are useful in integral multilayer photosensitive elements such as those disclosed in the previously mentioned copending application, Serial No. 748,421. As examples of suitable coating solutions which may be used to apply the cyan, magenta and yellow dye developer layers in such elements, mention may be made of:

(l) A tetrahydrofuran-methanol solution (1 to 1 by volume) comprising 5.5% of 1,4-bis-[18-(2,5'-dihydroxyphenyl)-isopropylamino]-anthraquinone (a cyan dye developer prepared in a manner similar to that disclosed in the previously mentioned copending application, Serial No. 478,922) and 2% of a N,N-diethylacrylamide-acrylamide copolymer, prepared as in Example 2.

(2) A tetrahydrofuran-methanol solution (1 to 1 by volume) comprising 3.5% of 2-[p-(2,5-dihydroxyphenethyl) -phenylazo]-4-n-propoxy-1-naphthol (a magenta dye developer prepared in a manner similar to that disclosed in the previously mentioned copending application, Serial No. 612,045) and 2% of a N,N-diethylacryl amide-acrylamide copolymer, prepared as in Example 2.

(3) A tetrahydrofuran-methanol solution (1 to l by volume) comprising 3.0% of 1-phenyl-3-N-nhexylcarbamyl-4-[p-(2',5-dihydroxyphenethyl) phenylazo]-5- pyrazolone (a yellow dye developer prepared in a manner similar to that disclosed in the previously mentioned copending application, Serial No. 612,045) and 2% of N,N-diethylacrylamide-acrylamide copolymer as prepared in Example 2.

In certain instances minor irregular patterns, e.g., slight waviness, may be observed in the monochrome and multicolor transfer images produced from the photosensitive elements of this invention. Such patterns, which detract only slightly from the good overall photographic qualities of the image, appear to occur most frequently when aqueous coating solutions are used to apply the layers which are to be directly over the copolymer layers of this invention. Although the cause of such patterns is not known for certain, it is believed that in the coating amount of a operation the water of the coating solution permeates the copolymer layers and causes slight swellings and distortions which are transmitted to the transfer image. It has been discovered that such minor irregular patterns may be substantially eliminated by incorporating a small hydrophobic polymer into the copolymer lay ers of this invention. As examples of hydrophobic polymers which have been found especially useful, mention may be made of cellulose acetate and cellulose nitrate. The amount of hydrophobic polymer added may be varied to suit particular needs. Usually an amount equal to about 25% of the copolymer will produce the desired results.

The copolymers of this invention are further suitable for use in screen type photosensitive elements such as disclosed in the aforementioned application of Howard G. Rogers, Serial No. 748,421 and also the copending application of Edwin H. Land, Serial No. 448,441, filed August 9, 1954, now US. Patent No. 2,968,554 issued January 17, 1961, wherein at least two selectively sensitized silver halide emulsions are arranged in the form of a screen and the color-providing substances, as in multilayer photosensitive elements, are preferably placed in a separate alkali-permeable layer in back of the photosensitive emulsion with which they are associated.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A photosensitive element for color diflusion transfer processes comprising a support bearing at least one silver halide emulsion layer and a polymeric layer contiguous with said silver halide emulsion layer having a colorproviding substance selected from the group consisting of dyes and dye intermediates disposed therein, said polymeric layer comprising a polymer selected from the group consisting of (A) copolymers of N,N-dialkylamide of an c p-unsaturated aliphatic monocarboxylic acid comprising less than six carbon atoms "and each N-alkyl group comprising less than five carbon atoms and a comonomer selected from the group consisting of a,;3-unsaturated aliphatic monocarboxylic acids comprising less than six carbon atoms and unsubstituted amides of said acids and (B) copolymers of an c p-unsaturated aliphatic monocarboxylic acid comprising less than six carbon atoms and a comonomer selected from the group consisting of N-cycloalkyl-substitutedand N-aralkyl-substituted-u,/3- unsaturated carboxamides, said carboxamide being a derivative of an a,fi-unsaturated aliphatic monocarboxylic acid comprising less than six carbon atoms and the N- cycloalkyl and N-aralkyl substituents of said carboxamides comprising less than eight carbon atoms.

2. A photosensitive element as defined in claim 1 wherein said color-providing substance is a dye developer.

3. A photosensitive element as defined in claim 1 wherein said polymeric layer is between said support and said silver halide emulsion layer.

4. A photosensitive element as defined in claim 1 wherein said polymeric layer comprises a copolymer within group (A) and each of the N-alkyl substituents in said N,N-dialkylamide monomer used to prepare said copolymer comprises less than three carbon atoms.

5. A photosensitive element as defined in claim 4 wherein the molar ratio of said N,N-dialkylamide monomer to the comonomer reactant used to prepare said copolymer is at least 1 to 1.

6. A photosensitive element as defined in claim 1 wherein said polymeric layer comprises a copolymer within group (A) and each of the N-alkyl substituents in said N,N-dialkylamide monomer comprises four carbon atoms and the ratio of said N,N-dialkylamide 10 monoiner to the comonomer reactant used copolymer is less than I to 1.

7. A photosensitive element as defined in claim 1 wherein said copolymer is made from N,N-diethylacrylamide and acrylamide.

8. A photosensitive element as defined in claim 1 wherein said polymeric layer comprises a copolymer within group (B) and the molar ratio of the comonomer reactant to the il-unsaturated carboxylic acid monomer used to prepare said copolymer is at least about 1 to 1.

. 9. A photosensitive element as defined in claim 1 wherein said copolymer is made from N-cyclohexylacrylamide and acrylic acid.

silver halide emulsion layer of a photosensitive element is developed to provide an imagewise distribution of colorproviding substances selected from the group consisting of dyes and dye intermediates in said emulsion, and said imagewise distribution of color-providing substances is by an aqueous alkaline processing solution to a superposed image-receiving layer to impart to said image-receiving layer a color image, the improvement comprising having a color-providing substance in a polymeric layer behind the silver halide emulsion layer and, during processing, permeating said photosensitive element with said aqueous alkaline processing solution and solubilizing said color-providing substances from said polymeric layer, said polymeric layer comprising a polythe group consisting of (A) copolymers of a N,N-dialkylamide of an cap-unsaturated aliphatic monocarboxylic acid which exclusive of the N,N- dialkyl substituents comprises less than six carbon atoms and a comonomer selected from the group consisting of n p-unsaturated aliphatic monocarboxylic acids comprising less than six carbon atoms and unsubstituted amides of said acids and (B) copolymers of an a,,B-unsaturated aliphatic monocarboxylic acids comprising less than six carbon atoms and a comonomer selected from the group consisting of N-cycloalkyl-substitutedand N-aralkyl-substituted-a,,B-unsaturated carboxamides, said carboxamides being derivatives of c d-unsaturated aliphatic monocarboxylic acids comprising less than six carbon atoms and said N-cycloalkyl and said N-aralkyl substituents comprising less than eight carbon atoms.

11. In a process of forming transfer images in color which comprises exposing a photosensitive emulsion containing a silver halide emulsion layer and a polymeric laysaid polymeric layer containing a dye developer, said least a portion of said mobile dye developer to a superposed image-receiving layer to form a positive image, the improvement comprising having the dye developer in a polymeric layer of a polymer selected from the group consisting of (A) copolymers made from a N,N-dialkylamide of an a,B-unsaturated aliphatic monocarboxylic acid which exclusive of the N-N-dialkyl substituents comprises less than six carbon atoms and comonomers selected from the group consisting of c d-unsaturated aliphatic monocarboxylic acids comprising less than six carbon atoms and unsubstituted amides of said acids and (B) copolymers made from an 0a,,B-11l1SfltIl1'3t6d aliphatic monocarboxylic acids comprising less than six carbon atoms and a comonomer selected from the group consisting of N-cycloalkyl-substitutedand N-aralkyl-substito prepare said tuted-a,5-unsaturated carboxamides, said carboxamides being derivatives of u,;3-unsaturated aliphatic monocarboxylic acids comprising less than six carbon atoms and said N-cycloalkyl and said N-aralkyl substituents comprising less than eight carbon atoms.

12. A process as defined in claim 11 wherein said polymeric layer comprises a copolymer withingroup (A) and each of the amide monomer used to prepare said copolymer comprises less than three carbon atoms.

13. A process as defined in claim 12 wherein the molar ratio of said N,N-dialkylamide monomer to the comonomer reactant used to prepare said copolymer is at least' 14. A process as defined in claim 11 wherein said polymeric layer comprises a copolymer within group (A) and each of the N-alkyl substituents in said N,N-dialkylamide monomers comprises four carbon atoms and the ratio of said N,N-dialkylamide monomer to the comonomer reactant used to prepare said copolymer is less than 1 to 1.

N-alkyl substituents' in said N,N-dialkyl- 15. A process as defined in claim 11 wherein said copolymer is made from N,N-diethylacrylamide and acrylamide.

16. A process as defined in claim 11 wherein said polymeric layer comprises a copolymer within group (B) and the molar ratio of the comonomer reactant to the a,fi-unsaturatedcarboxylic acid monomer used to prepare said copolymer is at least about 1 to 1.

17. A-process as defined in claim 11 wherein said c0- polymer is made from N-cyclohexylacrylamide and acrylic acid.

References Cited in the file of this patent UNITED STATES PATENTS 2,744,668 Rogers Dec. 18, 1956 2,831,826 Coover et a1 Apr. 22, 1958 2,843,562 Caldwell July 15, 1958 2,892,710 Cohler et al. June 30, 1959 

10. IN A PROCESS OF FORMING A PHOTOGRAPHIC IMAGE IN COLOR WHEREIN A LATENT IMAGE CONTAINED IN AN EXPOSED SILVER HALIDE EMULSION LAYER OF A PHOTOSENSITIVE ELEMENT IS DEVELOPED TO PROVIDE AN IMAGEWISE DISTRIBUTION OF COLORPROVIDING SUBSTANCES SELECTED FROM THE GROUP CONSISTING OF DYES AND DYE INTERMEDIATES IN SAID EMULSION, AND SAID IMAGEWISE DISTRIBUTION OF COLOR-PROVIDING SUBSTANCES IS TRANSFERRED BY AN AQUEOUS ALKALINE PROCESSING SOLUTION TO A SUPERPOSED IMAGE-RECEIVING LAYER TO IMPART TO SAID IMAGE-RECEIVING LAYER A COLOR IMAGE, THE IMPROVEMENT COMPRISING HAVING A COLOR-PROVIDING SUBSTANCE IN A POLYMERIC LAYER BEHIND THE SILVER HALIDE EMULSION LAYER AND, DURING PROCESSING, PERMEATING SAID PHOTOSENSITIVE ELEMENT WITH SAID QUEOUS ALKALINE PROCESSING SOLUTION AND SOLUBILIZING SAID COLOR-PROVIDING SUBSTANCES FROM SAID POLYMERIC LAYER, SAID POLYMERIC LAYER COMPRISING A POLYMER SELECTED FROM THE GROUP CONSISTING OF (A) COPOL MERS OF A N,N-DIALKYLAMIDE OF AN A,B-UNSATURATED ALIPHATIC MONOCARBOXYLIC ACID WHICH EXCLUSIVE OF THE N,NDIALKYL SUBSTITUENTS COMPRISES LESS THAN SIX CARBON ATOMS AND A COMMONOMER SELECTED FROM THE GROUP CONSISTING OF A,B-UNSATURATED ALIPHATIC MONOCARBOXYLIC ACIDS COMPRISING LESS THAN SIX CARBON ATOMS AND UNSUBSTITUTED AMIDES OF SAID ACIDS AND (B) COPOLYMERS OF AN A, B-UNSATURATED ALIPHATIC MOMOCARBXYLIC ACIDSS COMPRISING LESS THAN SIX CARBON ATOMS AND A COMONOMER SELECTED FROM THE GROUP CONSISTING OF N-CYCLOALKYL-SUBSTITUTED-AND N-ARALKYL SUBSTITUTED-A, B-UNSATURATED CARBOXAMIDES, SAID CARBOXAMIDES BEING DERIVATES OF A, B-UNSATURATED ALIPHATIC MONOCARBOXYLIC ACIDS COMPRISING LESS THAN SIX CARBON ATOMS AND SAID N-CYCLOALKYL AND SAID N-ARALKYL SUBSTITUENTS COMPRISING LESS THAN EIGHT CARBON ATOMS. 